_root.createTextField("myVar", 1, 0, 0, 100, 20);
//可输入
_root.myVar.type = "input";
_root.myVar.text = "123456789";
//监听事件
someListener = new Object();
someListener.onSetFocus = function() {
  //
};
Selection.addListener(someListener);
//焦点设在myVar上
Selection.setFocus("_root.myVar");
//捕获2－4个字符
Selection.setSelection(1, 5);
//返回获得焦点的对象引用
trace(Selection.getFocus());
//返回选择的开始索引
trace(Selection.getBeginIndex());
//返回选择的结尾索引
trace(Selection.getEndIndex());
//返回光标位置
trace(Selection.getCaretIndex());

注意在编辑环境selection无效，生成swf后单独测试